KR100297636B1 - Availability anodes of electroplating equipment - Google Patents

Abstract

Soluble anodes, which are used for electroplating coated metals, such as nickel, on a moving metal plate, are provided as a means of making a fixed or electrical contact for the supplied current with an anode body made of the above-mentioned coated metal extending longitudinally. It consists of an anode head.

According to the invention, the anode head constitutes a metal floor (63, 64) that is volumetrically connected to the anode body to ensure temporary mechanical connection of the head to the anode body and to electrically connect them. The anode body, on the other hand, is allowed to reuse the anode head after removing the weld (40).

Description

Fusible Anode of Electroplating Equipment

1 is a schematic diagram of the main part of an electroplating installation according to the prior art, using a soluble anode (for example nickel) which can be moved by a bar for supply and support of current; The sheet metal, which is subjected to electroplating of the anode metal and supported by a cylindrical roll of insulating material except for the central electrically conductive portion, constitutes the cathode.

2 is a front view of the installation according to arrow II of FIG.

3 is a plan view of the plant according to arrow III of FIG.

4 is a side view of the apparatus for forming the anode according to the prior art, showing that the anode head is permanently attached to the anode body.

5 shows a positive electrode according to the present invention having a weld bead between the intermediate plate and the positive electrode body bonded to the positive electrode head, and after the positive electrode body is consumed, the intermediate plate can be cut several times.

The present invention relates in particular to an electroplating apparatus having a soluble anode, which is used for coating (plating) steel with nickel or zinc-nickel, and more particularly to producing such a soluble anode.

In line with the ever-increasing demand for enhancing the corrosion stability of exposed parts of automobiles, such as the bodywork, the automotive industry has found that soft steel sheets coated with thin protective films made of zinc or zinc-based alloys such as zinc-nickel have been used. Became known.

In particular to improve the adhesion of the zinc layer to steel, a multi-coated sheet metal technique has been developed, which is to coat (plat) one or more intermediate layers, for example nickel, between the steel and the outer zinc layer. .

Industrially, the technique involves placing a series of electrolysers on a galvanized line through which the sheet metal to be coated is passed, which is passed through several return rolls immersed in a container filled with electrolyte.

The desired results can be obtained by following typical electrolytic parameters such as anode current density, electrolyte composition, and rate of travel.

In nickel plating, conventional plating methods use nickel salts, such as nickel chloride in solution state, which produce good results but exhibit many problems in use.

For example, storage of nickel salts involves research work to deal with the loss problem associated with it. Another more serious drawback is the release of nickel salt dust into the atmosphere, which can pose a danger to people exposed to it.

In addition, these electrolysers become progressively more concentrated with undesirable elements.

To avoid these problems, steel producers set out to use bulk nickel anodes with nickel to be plated. In this technique, the sheet metal to be treated is a cathode and the electrolyte occupies a gap between the electrodes. When the metal is coated on the sheet metal to be treated, it is moved in front of the anode so that the thickness of the anode decreases and the space between the electrodes (the surface of the nickel anode and the surface of the treated sheet metal or the cathode, accordingly) is correspondingly corresponding. Increases.

The anodes used in this technique are generally bulk anodes which are rolled, cut and bent in semi-continuously cast ingots. The thickness of the new anode is, for example, about 60 mm, but as it is used, the thickness decreases, increasing the space between the anode and the sheet metal and, if all other conditions are the same, the amount of nickel coated per unit time decreases. . Thereby, the amount of nickel coated per unit area along the sheet metal to be treated becomes nonuniform.

However, to overcome these drawbacks, measures are generally provided for the construction and operation of the installation.

Referring to FIG. 1 for a clearer understanding of this method, here is shown the arrangement of a generally known anode near the cylindrical roll through which the sheet metal to be treated rides through, constituting the cathode. The cylindrical roll 1 is made of an insulating material, away from the electrically conductive center portion. This part is in contact with the sheet metal to be treated, which is completely covered by the sheet metal and returns current to the generator.

The graphite support bar 2 lies laterally on the cylindrical roll 1 and has up to 12 anodes 3 inwardly bent, eg 1520 mm wide and 160 mm long.

2 shows that the second set of anodes are identically arranged on the support bar 4 which is located substantially in the opposite direction.

In order for the coating (plating) to be as uniform as possible, the anodes are moved along the bar 1 in the A direction, so that a new anode enters one side of the installation and the consumed anode exits on the other side.

FIG. 3 better illustrates the movement of the anode (s), which movement is to the sides of the cylindrical rolls supporting the sheet metal to be treated, with each other at the support bar 2 and the support bar 4. It is in the opposite direction. By constituting the movement of the anode in this way, the result is that the sum of the thicknesses of the two opposite anodes is always constant, and the sum of the distances (gaps) from the cathode is always constant.

For this reason, nickel is more uniformly coat | covered in parallel with the width and length of a sheet metal.

The apparent resistivity of the electrolyte is in the range of 10 ⁻² to 10 ⁻¹ Ωm, that is, at least 10 ⁵ times higher than metal conductors such as nickel with a resistivity of 7.10 ^-8 Ωm. This has two important conclusions:

First, the distribution of current density at the anode surface depends on the distance from the cathode toward each point of the anode. Because bulk nickel is more conductive than electrolyzers, the surface is always equipotential, whatever its shape and shape.

The second conclusion is that the resistance of the circuit is essentially due to the electrolyzer itself. This is reduced by minimizing the interelectrode gap, i.e. the distance between the anode surface and the sheet metal surface to be treated, thereby improving the energy balance. However, because the anode is consumed, as each individual anode moves along the support bar, the space between the electrodes increases and the current density that the anode receives decreases.

This results in that in the given example, the current density is not the same for all anodes. Increasing the space between the electrodes is undesirable because it locally increases the electrical resistance exhibited by the electrolyte, causing power loss and undesired heating of the electrolyte.

This consideration is very important because the current density is high, 100 A / dm ² or more on the surface of the anode.

To eliminate this effect, a graphite bar used as a support for the anode and a current inlet is placed inclined with respect to the axis of the cylinder. That is, the axis of the graphite bar is arranged obliquely with respect to the axis of the roll supporting the sheet metal. 3 shows that the anodes on each support bar 2, 4 move in opposite directions, and how the arrangement of the graphite bars at an angle with respect to the axis of the cylindrical roll 1 is a space or an anode between the electrodes. It shows whether the distance away from this roll 1 is kept constant. Thus, when an anode is used, the space between the electrodes remains constant at any moment, at any point, whatever the anode is.

The structure of the anode according to a known manner which constitutes the prior art of the invention is shown in FIG. The anode is fixed to the graphite bar using a hook 33 of a bulk anode head 31, which is a continuous weld beads (at least at the edge of the anode head). 32 is permanently welded to the anode body (30).

This embodiment is such that the anode head is perfectly firmly fixed and in optimum contact with the current inlet bar, in particular in perfect contact between the head and the anode body.

From the required geometrical point of view, the anode head cannot be cast directly, but is obtained by mechanically welding the nickel plate after cutting it to the specification in advance.

Therefore, it is analyzed that the manufacturing cost of this anode head is a large part of the total anode manufacturing cost.

Moreover, after the anode body is used, the entire anode, which is attached to the used anode body part and including the unused anode head, is recycled and recast.

The object of the present invention is to reduce the manufacturing cost of the anode while maintaining the rigidity of the anode body and good electrical contact with the anode body, and also to modify the system for fixing the anode head to the current supply bar. The anode can then be used in existing installations.

To this end, the subject of the invention is a soluble anode which is used to plate a coating metal on a moving sheet metal, the anode body consisting of the coating metal and extending in the longitudinal direction, and between the anode body and the anode head. Means for temporarily attaching the anode head to the anode body to ensure electrical contact to the anode body, wherein the temporary attachment means is an intermediate metal plate permanently coupled to the anode head and extending parallel to the anode body and welded to the anode body. It includes.

Thus, after the anode body is used, the head and the anode body can be separated without damaging the anode head. As a result, only the anode body is melted and regenerated, and the anode head is attached to the new anode body and can be reused.

This structure has an undeniable economic advantage, according to the invention, instead of all being melted and regenerated, the most complex part of the positive electrode holding system is attached to another anode and reused. This has a further advantage, as described above, because the current holding system or anode head is not actually touching the electrolyzer.

According to the present invention, between the main body and the anode head, an assembly base plate, which is installed in the anode head and is used as a part for making mechanical and electrical connections to the consumable anode head by welding the edges, if possible, is produced by It is easy to separate the anode body (for example by grinding weld beads).

This arrangement allows the anode head to be used again after removal of the welding bead, as long as the intermediate plate is relatively large compared to the anode head, so that the welding bead can be removed without damaging the anode head.

According to a particular arrangement, the plate extends in the longitudinal direction of the anode body and a weld bead is made and connected only at the end of the plate. This arrangement has the advantage of simplifying the task of coupling the anode head to the new anode body as much as possible, allowing for reliable electrical connection and optimum electrical contact without the risk of inducing secondary vortices such as voltage drops. In order to achieve this, it is sufficient to make two welding beads, which are as straight as possible, across the longitudinal direction of the anode body.

It should be noted that the current through the anode is typically very high 1000 to 2500 A. This high current must flow from the anode head to the body of the anode without any obstructions. It is therefore desirable to minimize the electrical resistance of the means for attaching the anode head to the anode body as much as possible; This resistance should be approximately as low as possible so as not to actually add resistance to the contact resistance (2.5 to 4.5 mΩ depending on the degree of wear of the anode) that exists between the anode supporting and supplying current bars and the anode head. Preference is given to lower than 0.1 mΩ.

If possible, the electrical resistance between the anode head and the anode body should be at least 25 times less than the contact resistance between the anode head and the bar.

In the case of the above example, the resistance between the head and the anode body can easily be less than 0.1 mΩ as described above, which resistance is seen across the current flow direction, ie along the longitudinal direction of the welding bead. Depends on the cross section.

It is clear that this resistance will have a very small value and can be easily reduced by simply increasing the size of the weld bead if desired.

In addition, the specific arrangement described above also has the advantage that the anode body can be easily separated from the anode head. In order to separate the anode head from the anode body, it is practically sufficient to cut the plate between the welding bead and the anode head across the longitudinal direction of the anode body. Since the plate is much larger than the anode head and has easy access to the area to be cut, cutting operations such as sawing or grinding can be easily performed without damaging the anode head.

It is recommended to cut the area as close to the weld bead as possible, which allows the plate to have the longest possible length after cutting.

Thus, after separation from the spent anode, the end of the plate is welded to the new anode body so that the anode head and the plate connected to it can be reused many times.

The length of the plate decreases with each cut, but this cut is made small enough by cutting as close as possible to the weld bead so that the weld bead can be reused many times before it gets too close to the anode head.

The welding beads should preferably be made of the same material as the anode.

Other features and advantages of the present invention will be described below, showing some embodiments of the anode according to the present invention.

The electroplating installations shown in FIGS. 1 to 4 have already been described in the above section detailing the features of the installation according to the prior art. A positive electrode according to the prior art shown in Figure 4, the anode body 30 extending in the longitudinal direction on the plane perpendicular to the axis of rotation of the roll (1) and bent inward, and a bar for supplying and supporting current (bar) A positive electrode head 31 is provided with a hook 33 for connecting to (2) (4).

The anode head is welded to the anode body with weld beads 32 along its entire edge.

One embodiment of the anode according to the present invention has been described with reference to FIG.

As can be seen, the means for connecting the anode head 61 to the anode body 40 is an intermediate plate permanently attached to the anode head 61 and extending to some extent from the anode head 61 parallel to the anode body. And (62). Therefore, the intermediate plate 62 has a curvature corresponding to the curvature of the anode body, and is connected to the anode body through the welding beads 63 and 64 at the ends thereof. Since the dimension of the intermediate plate in the longitudinal direction of the anode body is considerably larger than the height of the anode head, the welding bead is sufficiently far from the anode head 61, so that after the anode body is exhausted, the anode head is not damaged. The welding beads 63 and 64 can be removed to separate the anode body from the anode head.

The welding bead is preferably made only at the top and bottom of the plate 62 (FIG. 5) in a direction perpendicular to the longitudinal direction of the anode body.

Thus, after the anode body is exhausted, in order to separate the anode body from the anode head, cutting the end of the plate in parallel as close as possible to the welding beads 63, 64 (for example, by sawing or grinding) ) Suffice.

The cut end and the welding beads 63 and 64 remain attached to the anode body, but the remainder of the anode head 61 and the intermediate plate 62 are separated from the anode body and the ends of the plate 62 are replaced with new ones. It can be reused after connecting to a new anode body with a welding bead.

As long as the plate 62 is cut near the weld bead and the new end of the plate 62 is far from the anode head, several subsequent cuts 70, 71, 72, 73 and 74 ( 75) and welding, the anode head can be reused many times.

For example, in the case of a nickel anode, the intermediate plate 62 is also made of nickel and has a thickness of about 10 mm. The cross-sectional and length dimensions of the weld bead allow the current to flow properly.

In this example, a weld bead of length 160 mm constitutes a resistor having a length of about 10 mm in the direction of current flow, the cross section of which is made of nickel with a resistivity of 7.10 ^-8 Ωm: The resistance exhibited by the weld bead is 0.4 μΩ. The resistance here is 10 times less than in the previous case connected by bolted connections and does not cause electrical disturbances in the system.

Since the support plate 62 of the anode head becomes very short every time it is used, it is necessary to correct the exact position of the anode current supply point each time it is reused. However, this does not change the distribution of current density on the surface of the anode because the resistivity of the electrolyzer is at least 1000 times higher than the bulk metal constituting the anode, so that the entire anode is equipotential.

The present invention is not limited to the examples described above, but includes various modifications and similar cases within the scope of the claims.

Claims (6)

The anode body 40 is formed of a coated metal and extends in the longitudinal direction, and the anode head 41 is temporarily attached to the anode body 40 while ensuring electrical contact between the anode body and the anode head. And a temporary attachment means, which is permanently coupled to the anode head 61 and extends parallel to the anode body 40 and is connected to the anode body via weld connections 63 and 64. A soluble anode used to plate the coating metal on a moving sheet metal, comprising a metal plate 62. The soluble anode according to claim 1, wherein the intermediate plate (62) extends along the longitudinal direction of the positive electrode body, and a weld connection (63) is made only at the edge of the intermediate plate. 3. A soluble anode according to claim 2, wherein the weld connection (63) at the edge of the intermediate plate is made only at the end of the intermediate plate. The soluble anode according to any one of claims 1 to 3, wherein the weld connection (63) (64) consists of weld beads. The soluble anode according to claim 4, wherein the welding bead (63) is formed straight in the direction transverse to the longitudinal direction of the anode body (40). The soluble anode according to any one of claims 1 to 3, wherein the attachment means is made of the same material as the anode body (40).